Apparatus for actuating clam shell bucket

ABSTRACT

An improved clam shell digging apparatus is disclosed for digging deep rectilinear trenches in earth when raised and lowered by a crane or other lifting apparatus. The clam shell bucket is dependingly suspended from the top of the crane by inner and outer concentric pipes. A hydraulic cylinder at the top of the pipes causes relative movement between the inner and outer concentric pipes and opens and closes the clam shell bucket. The digging apparatus includes an improved bearing for preventing frictional wear between the inner and outer pipes when the bucket is opened and closed, an improved mounting of the bucket to the bottom of the inner and outer concentric pipes to prevent detachment of the bucket when it closes upon solid objects encountered in the earth; and an improved platform for maintaining the alignment of the bucket with respect to the crane.

United States Patent [151 3,684,040 Heacox [4 1 Aug. 15, 1972 [54] APPARATUS FOR ACTUATING CLAM Primary Examiner-David H. Brown SHELL BUCKET Attorney-Townsend and Townsend [72] Inventor: Russel L. Heacox, Santa Rosa, Calif. [57] ABSTRACT [73] Asslgnee' z South San Fran- An improved clam shell digging apparatus is disclosed clsco, Calif. for digging deep rectilinear trenches in earth when [22] File June 24, 1970 raised and lowered by a crane or other lifting apl A LN 49 469 paratus. The clam shell bucket is dependingly 1 PP suspended from the top of the crane by inner and outer concentric pipes. A hydraulic cylinder at the top U-S. Clof the causes relative movement between the [51] lltt. Cl. ..EZlb 9/32 inner and outer concentric pipes and opens and closes [581' F'eld Search "175/173, the clam shell bucket. The digging apparatus includes 175/284242 an improved bearing for preventing frictional wear between the inner and outer pipes when the bucket is [56] References cued opened and closed, an improved mounting of the v UNITED STATES PATENTS bucket to the bottom of the inner and outer concentric pipes to prevent detachment of the bucket when it upon in 1,474,707 11/1923 Crow] ..l75/285 X and an improved platform for maintaining the ahgh 2,63 L013 3/1953 Dar n 1 75/285 X mem f the bucket with respect to the crane 2,719,698 10/1955 Darin et al ..l75/202 4 Claims, 14 Drawing Figures PATENTEII I 5 3.6 84,040

SHEET 1 [IF 4 IE"; I F if! I I I I I I I I I I I I I I I I I I I I I I I w I I 74 II E l I 72 I I I 22 2 F|G 1 I4 I INVENTOR- RUSSEL L. HEACOX BY I ATTORNEYS PATENIEDAus 15 I972 sum 2 or 4 INVENTOR. RUSSEL L. HEACOX ATTORNEYS PATENTED 3.684, 040

snmuura RUSSEL L. HEACOX BY W 1W ATTORNEYS APPARATUS FOR ACTUATING CLAM SHELL BUCKET The invention relates to a digging apparatus of the clam shell type and more particularly to a clam shell bucket designed to dig a deep rectilinear trench.

Recent developments in heavy foundation construction have made necessary the digging of deep rectilinear trenches within the earth. .One extremely convenient way to dig such trenches is through the use of clam shell buckets attached to and actuated by elongate relatively movable members such as inner and outer concentric pipes. With the clam shell bucket attached to the bottom of such inner and outer concentric pipes and an actuating hydraulic cylinder attached to the top of such inner and outer concentric pipes, the clam shell bucket can be opened and closed with great force. Moreover, the weight of the clam shell bucket and attached pipes gives improved digging. Additionally, the hydraulic cylinder can be placed in a position where it is above ground at all times; when digging of a rectilinear trench occurs through a fluid, such as a bentonite slurry, the hydraulic cylinder is maintained at all times out of contact with the fluid. Fouling of the cylinder with either the fluid or particles suspended in the fluid is avoided.

Heretofore clam shell buckets of the type described have had considerable problems. These problems include maintaining the precise alignment of the clam shell relative to the crane which raises and lowers it. Additionally, when the clam shell bucket closes on solid objects, such as rock, piles and the like in the soil, it frequently shears free of its supporting and actuating pipes. Moreover, continuous opening and closing of the bucket has resulted in rapid frictional wear between the relatively movable members adjacent the clam shell bucket.

An object of thisinvention is to provide for alignment of the clam shell bucket with respect to the crane or other lifting apparatus from which it is raised and lowered in depending relation. Accordingly, one of the relatively movable members is provided with a longitu dinal key extending substantially the entire length of the member. This key is faced towards the crane or other lifting apparatus. A keyway is mounted on a platform held at the lower end of the member. The keyway extends around the member and mates with the key on the member. When the clam shell bucket is raised and lowered, rotation of the keyway permits rotational alignment of the clam shell bucket during digging.

An advantage of this key and keyway construction is that during lowering of the clam shell into the earth, precise angular positioning of the clam shell can occur relative to the crane.

A further advantage of this invention is that during raising of the clam shell from its digging position interior of the earth, the key and keyway disposed toward the crane are unloaded to prevent jamming or wedging of the key and keyway.

An additional object of this invention is to provide for an attachment of the clam shell to an outer concentric pipe for compressively loading this pipe on bucket closure. According to this aspect of the invention, connection of the bucket to an outer concentric pipe is provided at a flange which is slipped over and fastened to the lower end of the outer concentric pipe. When bucket closure occurs, the outer pipe is compressively loaded at its lower circular end around its entire periphery.

An advantage of this compressive loading of an outer pipe during bucket closure is that shearing or parting of the connection between the clam shell bucket on one hand and the outer concentric pipe on the other hand is avoided.

A further advantage of this compressive loading of the outer concentric pipe is that the entire periphery of the pipe can be loaded in compression; concentration of stresses within the outer concentric pipe is avoided.

Yet another object of this invention is to provide a bearing surface between the relatively movable mem bers adjacent the clam shell bucket for entering the member relative to one another.

An advantage of the bearing surface provided adjacent the clam shell bucket is that wear between the relatively movable members is held to a minimum.

Yet another advantage of the: bearing surface adjacent the clam shell bucket is that the jaws of the clam shell bucket come together in engagement on a plane which is axially aligned to the longitudinal axis inner and outer concentric pipes.

Other objects, features and advantages of this invention will become more apparent after referring to the following specification and attached drawings in which:

FIG. I is a side elevation of a crane dependingly supporting the clam shell digging apparatus of this invention;

FIG. 2 is an expanded side elevation of the platform and platform support used for aligning the clam shell digging bucket with respect to the crane during lowering and raising of the bucket into and out of the earth;

FIG. 3 is a front elevation view of the platform along lines 3-3 of FIG. 2;

FIG. 4 is a plan view of the platform shown in FIG. 2;

FIG. 5 is an enlarged plan view of the keyway used for orienting the clam shell bucket with respect to the crane;

FIG. 6 is an enlarged side elevation of the clam shell bucket and attached inner and outer concentric actuating pipes;

FIG. 7 is a front elevation of the clam shell bucket shown in FIG. 6;

FIG. 8 is a detail of the attachment used for compressively loading the outer pipe upon bucket closure;

FIG. 9 is a section taken along lines 9-9 of FIG. 8 illustrating the bearing surface used for preventing frictional and abrasive wear between the inner and outer concentric pipes adjacent the clam shell bucket;

FIG. 10 is a side elevation view, partially broken away, showing the inner concentric pipe and its attachment to the outer concentric pipe at the top portion and its attachment to the clam shell bucket at the bottom portion;

FIG. 11 is a front elevation similar to FIG. 10;

FIG. 12 is a sectional view taken along lines 12-l2 of FIG. 11; a

FIG. 13 is a sectional view taken along lines 13-43 ofFIG. l l; and,

FIG. 14 is a sectional view taken along lines 14 14 of FIG. 1 1.

Referring to FIG. 1, the digging apparatus of this invention is illustrated. The digging apparatus includes a clam shell bucket A connected at the bottom to inner concentric pipe B and outer concentric pipe C. Opening and closing of the clam shell bucket A is effected by hydraulic cylinder F causing relative movement between the inner concentric pipe B and the outer concentric pipe C.

The digging apparatus is dependingly supported from a crawler crane 14 having boom 16. Boom 16 has cable 18 threaded therein and attaches to the upper end of inner and outer concentric pipes B and C at eye 17. Crane 14 through cable 18 and eye 17 serves to raise and lower the digging apparatus into and out of the earth.

Alignment of the clam shell bucket A with respect to crawler crane 14 is accomplished by a male key D extending longitudinally on the outside of outer concentric pipe C and keyway E carried on a platform adjacent the lower portion of boom 16 of crawler crane 14. The key D, attached to the outer concentric pipe C, and keyway E supported from the lower end of boom 14, function to align the clam sheet bucket A with respect to the crawler crane 14. When precise alignment of the clam shell bucket A with respect to crawler crane 14 is achieved, clam shell bucket A can dig a precise rectilinear trench within the earth.

In the understanding of this invention, it will be convenient to segment the operative features of this invention. Accordingly, the function of the key D and keyway E in aligning clam shell bucket A with respect to crawler crane 14 will first be discussed. Thereafter, the attachment of the clam shell bucket A to the inner and outer concentric pipes B and C will be set forth. Finally, the configuration and construction of the upper portion of the digging apparatus adjacent cable 18 and eye 17 will be discussed.

Referring to FIG. 1, it will be seen that platform connected to crawler crane 14 at the bottom of boom 16 extends around outer concentric pipe C. Typically, platform 20 is dependingly supported by cable 19. Cable 19 is typically rigged from a middle of boom 16 to an outer portion of the platform through rigging which passes on either side of outer concentric pipe C.

Platform 22 supports keyway E at a constant elevation during raising and lowering of bucket A into and out of the earth. This keyway E maintains a spatial interval between crawler crane 14 on one hand, and the digging apparatus of this invention on the other hand. More importantly, it functions to align bucket A with respect to crawler crane 14.

Framework 20 is anchored at the lower end of boom 16 by two bearings 21, each bearing being located at and riding on shaft 22 on boom 16. Bearings 21 are in turn fastened to paired I-beams 23. I-beams 23 extend angularly outward and upward from crane boom 16 at their lower ends to support keyway E at their upper ends. As shown in the views of FIGS. 1 and 2, l-beams 23 are disposed and maintained at an angle of approximately 75 with respect to horizontal when the crane is rigged for operation.

In addition to paired I-beams 23, frame 20 includes a pair of upper bars 24. Bars 24 each begin at bearing 21 and extend upwardly and angularly overlying the lbeams 23 to a position overlying the keyway E at 25. Between the keyway E on one hand and bearings 21 on the other hand, I-beams 23 and bars 24 are intercon nected and spaced by vertical bracing 27. Similarly beams 23 are interconnected and spaced by horizontal bracing 28.

Keyway E is rested on and supported by I-beams 30 and 32. I-beams 30 are each supported on the ends of I- beams 23 and are substantially horizontal. I-beams 32 are at right angles to I-beams 30, placed adjacent the ends of the I-beams 30, and together with l-beams 30 define a square frame or opening on which keyway E rests.

Keyway E is fabricated for sliding insertion into and out of platform 20. To this end, I-beams 32 each support a pair of L-shaped ways 34. Ways 34 grip the side edges of the keyway E and permit it to be removably inserted into and out of a position on platform 20.

Referring to FIG. 5 it will be seen that keyway E includes a square plate 36 having two parallel side edges 37 and parallel front and rear edges 38. Typically, side edges 37 are each spaced so that they can be received within ways 34 and securely held.

When plate 36 supporting keyway E is inserted interior of ways 34, it is necessary that the plate be keyed in place. Such keying is accomplished by longitudinal slots 40 adjacent front and rear edges 38 of plate 36 and bars 42 complementary to slots 40 (see FIGS. 5 and 3). Typically, plate 36 is positioned interiorly of ways 34 so that slots 40 each overlie the bars 42. Thereafter the bars are raised and bolted to secure plate 36 firmly to the platform 20.

Rectangular plate 36 includes circular aperture 45. Resting on aperture 45 there is a metallic ring 46 having an outside diameter 47 greater than the inside diameter of circular aperture 45 in plate 36. Thus it will be seen that ring 46 when rested on plate 36 will not fall through aperture 45.

it is necessary that ring 46 be braced on plate 36 overlying hole 45. Such bracing must prevent up and down movement of the ring 46 in response to the up and down movement of pipes B and C during digging. Accordingly, four ring guides 50 are each secured to plate 36 adjacent each comer thereof. Guides 50 position ring 46 overlying aperture 45. Ring 46 is free to rotate inside of the guides 50 but is not free to move away from plate 36, or slide transversely over the surface of plate 36.

Ring 46 has a series of holes 52 drilled therein. Complementary to holes 52 and placed within guides 50 and plate 36 there are securing apertures 54. As is apparent, by placing pins through securing apertures 54 and registered apertures 52 in ring 46, the rotational alignment of ring 46 with respect to plate 36 can be made fast.

During digging with clam shell bucket A, pipes B and C will move upwardly and downwardly interior of the hole and keyway E defined interior of ring 46. To facilitate such movement, ring 46 is provided with four rim mounted casters 58 at radial intervals. These rim mounted casters each have axes of rotation which are tangent to the periphery of aperture 49 of ring 46 and are spaced one from another at intervals which are slightly larger than the diameter of exterior concentric pipe C. When pipe C moves into and out of the ground, casters 58 ride on outer pipe C and center it in aperture 59 of ring 46.

Outer pipe C has key D welded thereto. Key D typically comprises a piece of barstock 62 extending the full length of outer pipe C from a position adjacent clam shell bucket A to a position ad pining the top of the lifting apparatus. This barstock 62 provides the key D which rides interior of keyway E and serves to rotationally positioned the clam shell bucket A relative to crawler crane 14.

Keyway E includes a rectangular aperture 64 cut in the interior diameter 59 of frame 46. Mounted to either side of the keyway D are two rollers 68. Rollers 68 bear against the side edges of rectangular barstock 62 and align outer pipe C radially interior of the aperture 59 in ring 46.

Referring to FIG. 1, it will be noted that key D faces towards crawler crane 14. It has been found that when clam shell bucket A is closed upon earth and is lifted out of a rectilinear trench interior of the earth, boom 16 flexes outwardly and downwardly towards the earth (see broken lines 70 in FIG. 1). When such flexure occurs, outer pipe C bears against the outer portion 72 of the platform with great force. It has been found that if the key D and keyway E are positioned adjacent the outer portion of the platform at 72, a wedging of the key D interior of the keyway E can occur. Accordingly, the apparatus of this invention is constructed and arranged with the key D and the keyway E positioned at 74. Key D and keyway E are both placed facing generally towards the boom 16. With this arrangement, the movement of the outer pipe C towards point 72 on platform 20 does not cause a wedging and jamming of the key D interior of the keyway E. Smooth and uninterrupted digging is thus permitted.

Having described the interrelation of key D and keyway E, the construction and design of clam shell bucket A can be described. Thereafter, the securing of the clam shell bucket to the outer concentric pipe C will be set forth. This will be followed by a description of the securing of the clam shell bucket to outer concentric pipe C.

Clam shell bucket A is of generally conventional construction. Typically, central pivot shaft 80 pivotally conjoins the apex of two pie sectioned bucket shells. Each clam shell has leading or digging edge 81, trailing edge 82 and is provided with an arcuate bottom wall 83. Opening and closure of the respected shells is effected through arms 85 pivotally attached to shafts 86 adjacent trailing edge 82 and bottom wall 83. Arms 85 are attached at their opposite end to thrust collar 88 secured to outer pipe C.

In operation, when the bucket is open, inner pipe B moves downwardly and out of outer pipe C. This motion thrusts pivot 80 away from thrust collar 88 (see bucket position illustrated in broken lines FIG. 6).

Each shell of the bucket pivots around two points. One point is the downwardly moving shaft 80. The other point is the shaft 86 adjacent trailing edge 82 and bottom wall 83. The resultant combined movement is that the confronting edges 81 of each shell are downwardly disposed for engagement with the earth (see broken lines FIG. 6).

Conversely, when it is desired to close the clam shell bucket A, inner pipe B is drawn upward and into outer pipe C. Shaft 80 is pulled upwardly and towards thrust collar 88. The interconnection between inner pipe B on one hand and pivot 80 on the other hand will come under tension. Conversely, bars 85 connecting shaft 86 on the outer portion of each shell of the clam shell bucket A will be compressively loaded. Typically, bars 85 will push down on the clam shell bucket at points 86. Consequently, collar 88 will be compressively loaded as it bears against outer pipe C.

It has been found upon bucket. closure that thrust collar 88 is compressively loaded with considerable force. This force has been sufficient to cause shearing or tearing of the connection between the thrust collar 88 on one hand and the outer concentric pipe C on the other hand. Accordingly, it has been found desirable to 'provide for the compressive loading of the entire periphery of outer pipe C. Such compressive loading of the outer pipe C can be most conveniently illustrated with reference to FIGS. 8 and 9.

Referring to FIGS. 8 and 9, thrust collar 88 includes square plate 90. Plate 90 has two concentric and circular apertures 92 and 93 cut therein. Concentric aperture 92, the larger of the holes, has an inside diameter slightly larger than the outside diameter of outside pipe C. Concentric aperture 93, the smaller of the holes, has an inside diameter slightly larger than the outsid diameter of inner concentric pipe B.

Plate 90 and its concentric bores 92 and 93 serve two major functions. First, between aperture 92 and aperture 93 there is defined a small step 94. Step 94 accommodates the lower end of concentric pipe C. This is the member through which the lower end of concentric pipe C is compressively loaded around its entire periphery.

Additionally, the inside surface of smaller concentric aperture 93 bears against inner concentric pipe B as it is moved relative to outer concentric pipe C. This provides a bearing surface centering the concentric pipes B and C relative to one another. The pipes are held in concentric spatialrelation so that the outside wall of inner concentric pipe B does not rub against the inside wall of outer concentric pipe C.

Plate 90 has mounted along each side thereof four sections of barstock 96 notched-at notch 97. Notch 97 is centrally located in barstock 96 to enable opposing sides of each piece of the barstock to overlie the top and bottom surface of plate 90. Typically, barstock 96 is beveled at 98 for fastening by welding to the outside sidewalls of outer concentric pipe C.

Barstock 96 along opposite sides of plate 90 is cross bored at bores 99. Bores 99 serve to accommodate shafts 88 and are the members through which compressive loading from bars 85 occurs during bucket closure.

Having set forth the attachment of each of the clam shell buckets at shaft 86 to outer concentric pipe C, the attachment of the clam shell bucket at shaft 80 to inner concentric pipe B can be described. Referring to FIGS.

10-14, this attachment is illustrated. Typically, shaft 80 is rotably inserted interior of a concentric collar 100. Collar 100 is in turn encircled by two retaining rings 101 and 102. An inverted T-sha'ped member 104 is welded at the top horizontal member of the T at 105 to concentric collar 100. The outer sections of the T- shaped barstock and concentric collar 100 are each en'- circled and captured by rings 101 and 102 at notches 106. It can thus be seen that fastening of the concentric collar 100 to the T-shaped barstock occurs not only through welds at points 105 but additionally through the encirclement of the T-shaped bar by collars 101 and 102.

Attachment of T-shaped member 104 to the inside surface of inner concentric pipe B can be readily understood. Typically, this attachment occurs through two T-shaped members 110 and 111. Members 110 and 111 are spaced in parallel relation at the bottom vertical member of the T on either side of inverted T- shaped member 104. By cross boring these respective members with a bore 114 and inserting a shaft 115, a pivotal attachment between shaft 80 on one hand and the T-shaped members 110 and 111 on the other hand is effected.

T-shaped members 110 and 111 fasten to the inside sidewalls of inner concentric pipe B. This fastening occurs at surfaces 118. Typically, T-shaped members 110 and 1 11 as fastened interior of inner concentric pipe B are held in a spaced relation by spacers 120.

At the lower most portion of inner concentric pipe B, ring 122 is placed. Ring 122 is welded at its outside surface 123 to the inside bottom portions of inner concentric pipe B. This member fits over the bottom edges of the upper portion of T-shaped members 110 and 111 and serves to further fasten them interior of inner concentric pipe B.

Having set forth the attachment of inner concentric pipe B to shaft 80 of clam shell bucket A, the upper portion of the digging apparatus of this invention can be described. Referring to FIG. 1, it will be seen that hydraulic cylinder F is fastened to the top most portion of inner concentric pipe B. Referring to FIGS. 10, 11 and 13 this fastening is illustrated. Two rectangular steel plates 131 and 132 are inserted and welded interior of pipe B These members, initially held in spatial relation by spacers 134 and 135, are cross bored at 136. Typically, the lower end of hydraulic cylinder F is pinned to bores 136 through shaft 137. Thus, inner concentric pipe B is fastened to hydraulic cylinder F.

Hydraulic cylinder F has an outside diameter which is approximately the same as or slightly larger than the outside diameter of inner concentric pipe B. Thus it will be seen that hydraulic cylinder F at the upper most portion of the digging apparatus serves to center inner pipe B with respect to outer pipe C. Frictional contact of the outside surface of inner concentric pipe B with the inside surface of outer concentric pipe C is thus avoided along the entire length of the pipes.

Hydraulic cylinder F has paired tongues 141 and 142 protruding from the end of the cylinder. These tongues are cross bored at 143 to plate 150 and spacer plates 158 at the top of the digging apparatus. By the insertion of a shaft at 145, a connection between the cylinder F on one hand and plate 150 on the other hand is effected.

Plate 150 is a rectangular piece of metal which is placed in the top most portion of outer concentric pipe C in longitudinal slots 152. Slots 152 are notched in the side walls of outer concentric pipe C and extend downwardly along the sidewalls of the pipe.

Plate 150 is larger than the outside diameter of outer concentric pipe C. This plate is dimensioned so that it protrudes outwardly and beyond the sidewalls of outer concentric pipe C. Typically, pieces of barstock 154 are welded to outer concentric pipe C adjacent notches 152 and spaced so as to slideably receive therein the plate 150. By providing a series of cross bores in barstock 154 and plate 150, bolts 156 can be used to secure the barstock and plate 150 together.

It is usually desired to reenforce the aperture 143 bored within the plates 150. Accordingly, reenforcement plates 158 are fastened on either side of plate 150 and similarly cross bored. Plates 158 give the bore through which shaft 145 is inserted suflicient strength to resist mechanical forces when the clam shell bucket A is opened and closed.

It is desirable to assure that plate 150, reenforcement plates 158 and attached hydraulic cylinder F are centered interiorly of outer concentric pipe C. To this end spacer plates 160 are positioned and attached normally to each reenforcement plate 158 and extend from the plate to the inside wall of outer concentric pipe C.

Plate 150 and spacers 158 extend upwardly to a half rounded configuration at the upper end of outer concentric pipe C. Typically, a bore 162 is provided at this juncture. Bore 162 is the member through which eye 17 of cable 18 is fastened. As is apparent, bore 162 is the member through which the entire digging apparatus of this invention can be raised and lowered into the ground by the crawler crane.

It should be apparent to one skilled in the art that numerous modifications can be made without departing from the spirit of this invention. For example, the pipes here illustrated could be square as well as rectangular, one being placed interior of the other. Additionally, key D and keyway E could be given any number of varying configurations. Likewise, numerous other changes could be made without departing from the spirit and scope of this invention.

I claim:

1. In combination: a clam shell bucket having opposed shells movable about a common pivot to and from a first position where edges of said shell confront one another to capture earth to a second position where edges on said shells are open to receive and discharge earth; first and second vertically disposed relatively movable members supporting said clam shell bucket at their lower end; (means for actuating relative movement between said relatively movable members) each of said shells having a pivot point removed from said pivot by a preselected distance; one of said relatively movable members connected to said pivot and the other of said relatively movable members connected to said pivot points for moving said bucket between said first and second positions upon relatively movement between said members; said members operatively connected to said clam shell bucket at their lower end to move said bucket between said first position and said second position upon relatively movement between said members; a lifting apparatus including a support and a boom supported at the bottom and extending angularly from said support over the top of said relatively movable members; means for dependingly raising and lowering said relatively movable members from a point on said boom; a key on one of said relatively movable members extending a preselected distance along the vertical length of said member on a side thereof facing said boom; a framework pivotally connected to said support at one end and slideably engaging said relatively movable members at the other end; a keyway attached to and supported by said framework for engaging said key along a surface exposed away from said boom; said key in engagement with said keyway during raising and ing apparatus comprises a crawler crane.

4. The combination of claim 1 and wherein said keyway is supported on said boom at a point below said point on said boom from which said relatively movable members are dependingly raised and lowered. 

1. In combination: a clam shell bucket having opposed shells movable about a common pivot to and from a first position where edges of said shell confront one another to capture earth to a second position where edges on said shells are open to receive and discharge earth; first and second vertically disposed relatively movable members supporting said clam shell bucket at their lower end; (means for actuating relative movement between said relatively movable members) each of said shells having a pivot point removed from said pivot by a preselected distance; one of said relatively movable members connected to said pivot and the other of said relatively movable members connected to said pivot points for moving said bucket between said first and second positions upon relatively movement between said members; said members operatively connected to said clam shell bucket at their lower end to move said bucket between said first position and said second position upon relatively movement between said members; a lifting apparatus including a support and a boom supported at the bottom and extending angularly from said support over the top of said relatively movable members; means for dependingly raising and lowering said relatively movable members from a point on said boom; a key on one of said relatively movable members extending a preselected distance along the vertical length of said member on a side thereof facing said boom; a framework pivotally connected to said support at one end and slideably engaging said relatively movable members at the other end; a keywAy attached to and supported by said framework for engaging said key along a surface exposed away from said boom; said key in engagement with said keyway during raising and lowering relatively movable members to align at least one of said relatively movable members and attached clam shell bucket with respect to said boom.
 2. The combination of claim 1 and wherein said first and second vertically disposed relatively movable members include inner and outer concentric pipes.
 3. The combination of claim 1 and wherein said lifting apparatus comprises a crawler crane.
 4. The combination of claim 1 and wherein said keyway is supported on said boom at a point below said point on said boom from which said relatively movable members are dependingly raised and lowered. 